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148

PRACTICAL ORGANIC CHEMISTRY

tion indicates aniline.    2CBH3NH.NH.CCH5 = C0H6N:NC0H5=
2CGHi,NK,
2. Heat a small quantity with Fehling's solution and observe
the formation of cuprous oxide. The hydrazobenzene is oxidised
to azobenzene.
Benzidine.Five grams of powdered hydrazobenzene are
shaken with 125 c.c. hydrochloric acid (3 per cent.) at 2030. In
a quarter to half an hour the substance will have completely dis-
solved. Finally, the mixture is heated to 4550, a little water
added to redissolve any benzidine hydrochloride, and filtered
warm. The benzidine is precipitated from the solution of the
hydrochloride by adding to the cold solution an excess of caustic
soda solution. It is filtered and washed free from alkali, and 
recrystallised from boiling water or dilute alcohol. It crystallises
in plates with nacreous lustre, m. p. 127.
C6H5NH.NHCGH5 - NH2C0H4.C0H4NH3.
See Appendix, p. 275.
PREPARATION 52.
Phenylhydroxylamine, C0H5.NH.OH
Bamberger, Ber., 1894, 27,  1548; Wohl, Ber., 1894, 27, 1432 ;
Friedlander,  Theerfarbenfabrikation, IV.. 48.
6 grins, ammonium chloride (in 200 c.c. water).
12           nitrobenzene.
18     ,,      zinc dust.
Mix the nitrobenzene and ammonium chloride solution in a.
flask (i- litre). The zinc dust is added in portions of about a gram
at a time with constant shaking or stirring by turbine, the tem-
perature being maintained below 15, by cooling if necessary in ice
water. The addition of the zinc dust should take about an hour.
The shaking is continued for another quarter of an hour, when
the smell of nitrobenzene will have disappeared. The contents
of the flask are filtered and washed with 100 c.c. water, so that
the water trickles slowly through the filter. The filtrate is
saturated with clean salt (80 grams) and cooled to o. Colour-
less crystals of phenylhydroxylamine fill the liquid. They are
filtered at the pump, dried on a porous plate, and recrystallised
if necessary from benzene. Yield C8 grams.